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**[Solved] Total internal reflection, underwater light?**

## Homework Statement

A point source of light is at the bottom of a koi pond, at a depth of 0.525 meters. What is the radius of the circle of light formed on the water's surface? Take the index of refraction of water to be 1.33. Hint: Some of the light emitted experiences total internal reflection inside the water.

## Homework Equations

sin(crit angle) = n2/n1

n1>n2

n for air = 1.00

n for water = 1.33

## The Attempt at a Solution

So the critical angle for water to air is:

arcsin(1/1.33) = 48.7534666 degrees

This is where it all ends. There is no formula for distance or light radius. I am completely stuck at this point and cannot find anywhere in my book where I could derive the answer. I would deeply appreciate some help with this one!

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